Crop protection is nowadays mainly attained by means of a wide variety of pesticides. A large number of these is on the market, and they are highly effective. It is one of the drawbacks that crops tend to take up at least small quantities of such crop protection agents, and even if these are very small quantities, long-time effects are unpredictable and constitute a long range hazard. Some of the crop protection chemicals may cause over prolonged periods a wide variety of diseases and even malignancies. Furthermore, the growth of "organic crops" is gaining support, and these are grown under conditions avoiding the use of any synthetic chemicals.
The novel fencing means according to the invention are effective in greatly reducing the insect population of crop areas, yet provide adequate ventilation and air circulation.